6o C.C. NATURAL HISTORY SOCIETY. 



vary from 200 to 800 miles a day, and they are apparently borne 

 along by the prevailing breezes- 



The rainfall of any region depends on the prevailing winds con- 

 sidered in relation to regions from which they have come, and into 

 which they come. The colder the region they enter the more the rain. 

 General systematic observations of the rainfall of the country were 

 commenced in i860 by Mr. G. J. Symons, and he has now over 3,000 

 observers scattered over the British Isles. The whole of this work 

 is carried out by voluntary contributions, and the Government neither 

 recognize nor contribute towards the expense of this valuable work. 

 But before i860 there had been observations made for several years 

 in isolated places, and some of these go back for about 200 years. 

 The earliest known records in this country were taken at Bristol in 

 1774 to 1778. Length of time in observations is in nothing more 

 essential than in rainfall records, and it seems probable that 40 or 50 

 years at least of continuous observation are requisite in order to 

 obtain an accurate conception of the average yearly rainfall of any 

 place. I may say at once that rainfall observations are taken daily 

 at 9 a.m. and the amount measured is put down to the previous day. 

 Any day on which one-hundredth part of an inch falls is technically 

 known as a wet day. An inch of rain represents 100 tons of water 

 spread over an acre of land. It is no uncommon thing for an inch 

 of rain to fall in 24 hours in this country, and as much as 4 inches 

 in one day has been registered, for instance at Seathwaite (the wettest 

 place in England) last August 4^17 inches fell on the 5th, and 479 

 on the 26th, and the total rainfall for that one month exceeds by half 

 an inch the whole of the rainfall for the first 10 months of 1898 at 

 Cheltenham. But then Cheltenham is a dry place, its average annual 

 rainfall is only 28 inches, while that of Seathwaite is 136 inches. 

 But it does not follow that because a place has a heavy annual 

 rainfall that it is necessarily what people call a very wet place, that 

 is to say that it is always raining. Looked at from this point of view 

 Cheltenham is actually wetter than Seathwaite, relatively speaking, for 

 its percentage of wet days in a year works out at 50 while that of 

 Seathwaite is only 59, although the latter has nearly five times the 

 rain that Cheltenham has. A very interesting paper was recently 

 read before the Meteorological Society by Mr. Scott, the head of the 

 Government Department, in which he pointed out that the frequency 

 of the rainfall shifted from one part of the British Isles to another as 

 the year went on. In January the only places falling below 50 per 

 cent, are South Shields and Cambridge, while the West of Ireland 



